Fast Short Read De-Novo Assembly Using Overlap-Layout-Consensus Approach.

Abstract

The de-novo genome assembly is a challenging computational problem for which several pipelines have been developed. The advent of long-read sequencing technology has resulted in a new set of algorithmic approaches for the assembly process. In this work, we identify that one of these new and fast long-read assembly techniques (using Minimap2 and Miniasm) can be modified for the short-read assembly process. This possibility motivated us to customize a long-read assembly approach for applications in a short-read assembly scenario. Here, we compare and contrast our proposed de-novo assembly pipeline (MiniSR) with three other recently developed programs for the assembly of bacterial and small eukaryotic genomes. We have documented two trade-offs: one between speed and accuracy and the other between contiguity and base-calling errors. Our proposed assembly pipeline shows a good balance in these trade-offs. The resulting pipeline is 6 and 2.2 times faster than the short-read assemblers Spades and SGA, respectively. MiniSR generates assemblies of superior N50 and NGA50 to SGA, although assemblies are less complete and accurate than those from Spades. A third tool, SOAPdenovo2, is as fast as our proposed pipeline but had poorer assembly quality.